Automatic milking machines have traditionally relied on the fact that at the end of the milking process, the milk flow from a dairy animal (e.g., a cow, a goat, or any other milk-producing mammal) would slowly decrease from full flow to a low level that was designated as the detach flow rate. Normally, this decay time would take tens of seconds or even minutes to occur. This gave the detacher controls enough time to make a decision about when to remove the milking unit, and the user could make simple adjustments to have the cows milked out more completely (drier) or to leave more milk in the udder (wetter).
Recently, advances in milking equipment and procedures have changed this behavior. With proper equipment and cow preparation, cows can now be milked out in a much shorter time, and the milk flow may go from full flow to no flow in just a few seconds. If all of the milk is removed from the cow's udder and the unit remains on the teat for any length of time with no milk flow, the teat can be damaged. To prevent overmilking, users normally try to leave a small amount of milk in the udder. When the drop in milk flow was gradual, it was possible to use one standard detach threshold flow rate for most of the cows in the herd without over milking or under milking any of the cows significantly. With the new milking procedures, it is not possible to use a single threshold for all cows without over milking the high producing cows (who tend to drop off in flow rate faster at the end of the milking) or under milking the lower producers.
Pre-assigning individual thresholds to individual cows based on prior milking habits of each cow is not a practical solution because it requires a lot of manual effort to determine the correct thresholds and then enter and maintain the settings for all of the cows. It also requires that every cow be correctly identified during the milking process using electronic identification systems, and that each cow exhibits the same or similar milking characteristics each time the cow is milked.